Vermicomposting Process Research Articles

Vermicomposting of gastro waste does not produce high-quality fertilizer

AbstractThe production of gastro-waste is an common issue part in all societies, but its disposal, including recycling, is not yet satisfactorily resolved. This research explored whether it is possible to manage this waste directly at its source without special equipment and high initial investments. The study was conducted on a university campus, where a simple three-tier vermicomposter was assembled to process cafeteria leftovers. The vermicomposting process and the quality of the resulting vermicompost were monitored, and a container experiment with a 20% vermicompost concentration was set up.The vermicompost was evaluated from a food perspective and found to attract insects, emite odors, and heat up to over 50 °C within the vermicomposter. The resulting vermicompost parameters were not as favorable for agricultural use as those from thermally untreated waste. The most problematic parameter was the electrical conductivity, which likely caused the early termination of the container experiment due to plant death in the vermicompost-applied variant. Additionally, high concentrations of microorganisms such as Salmonella and E. Coli were found in the vermicompost. In conclusion, using the vermicomposting process for heat-treated food residues is not suitable for regular institutions. Graphical abstract

Humic Substances from Waste-Based Fertilizers for Improved Soil Fertility

This research explores how different organic waste transformation methods influence the production of humic substances (HSs) and their impact on soil quality. Using olive and orange wastes as substrates, the study compares vermicomposting, composting, and anaerobic digestion processes to determine which method produces the most humic-substance-rich products. The characterization of HSs in each product included analyses of total organic carbon (TOC), humic and fulvic acid content, humification rate, humification degree, and E4/E6 ratio, with HSs extracted using potassium hydroxide (KOH) and analyzed via Diffuse Reflectance Infrared Fourier-Transform (DRIFT) spectroscopy to assess structural complexity. The results revealed that the chemical composition of the input materials significantly influenced the transformation dynamics, with orange by-products exhibiting a higher humification rate and degree. Vermicomposting emerged as the most efficient process, producing fertilizers with superior humic content, greater microbial biodiversity, and enhanced cation exchange capacity, thus markedly improving soil quality. Composting also contributed to the stabilization of organic matter, albeit less effectively than vermicomposting. Anaerobic digestion, by contrast, resulted in products with lower levels of HSs and reduced nutrient content. Aerobic processes, particularly vermicomposting, demonstrated the most rapid and effective transformation, producing structurally complex, stable humus-like substances with pronounced benefits for soil health. These findings underscore vermicomposting as the most sustainable and efficacious approach for generating HS-rich organic fertilizers, presenting a powerful alternative to synthetic fertilizers. Furthermore, this study highlights the potential of organic waste valorization to mitigate environmental pollution and foster circular economy practices in sustainable agriculture.

Vermiculite changed greenhouse gases emission and microbial community succession in vermicomposting: Particle size investigation

Greenhouse gas emissions during composting inevitably cause environmental pollution. This study investigated the effects of 10 % vermiculite of four particle sizes (<1.5 mm, 1.5–3 mm, 3–5.5 mm and 5.5–8 mm) on greenhouse gas emissions during vermicomposting of corn stover and cow dung. The results revealed that vermiculite reduced CH4 and N2O emissions but increased CO2 emissions. Vermiculite with a particle size of 3–5.5 mm presented the greatest environmental benefits, increasing cumulative CO2 emissions by 19 % and reducing CH4 and N2O emissions by 49 % and 62 %, respectively. A negative correlation was found between the specific surface area of vermiculite and cumulative greenhouse gas emissions (r = −0.7949). Furthermore, vermiculite intensified microbial interactions and accelerated microbial community succession. These results have important implications for understanding how vermiculite regulates greenhouse gas emissions and microbial mechanisms during the vermicomposting process.

Characterization of the Agronomic Properties of Different Vermicompost from the Co-composting of Oil Palm Empty Fruit Bunches and Green Waste

The accumulation of palm oil industries waste is one of the causes of environmental pollution that is becoming an increasingly concern in Côte d'Ivoire. However, this waste, combined with other simple plant substrates, can be used in the vermicomposting process. That is the context in which this study is conducted, with the aim of determining the agronomic properties of different vermicompost made of oil palm empty fruit bunches combined with green waste (Chromolaena odorata leaves and grass clippings). For this purpose, plastic boxes of 1.5 L in volume were first filled with 800 g of soil. Then, 300 g of the different pre-composted substrates and 4 earthworms were added. In total, 4 treatments of 25 repetitions each were carried out. For all the treatments, treatments T3 (oil palm empty fruit bunches + Grass cutting + earthworms) and T4 (oil palm empty fruit bunches + Chromolaena odorata + Grass cutting + earthworms) presented the best values of the substrate decomposition capacity and physicochemical properties. The same is true for the mineral materials obtained. For these two treatments mentioned, the C/N ratio was around 15 and significantly higher than those of treatments T1 (oil palm empty fruit bunches + earthworms) and T2 (oil palm empty fruit bunches + Chromolaena odorata + earthworms), which were around 12. The pH values being variable at the beginning of vermicomposting were close to neutral at the end, thus indicating the maturity of the different vermicompost produced. Vermicompost resulting from co-composting of empty fruit bunches of oil palms and green waste appears to improve nutrient availability, structure and microbial activity of the vermicompost to promote good development of cultivated plants.

Efficacy of Chicken Feather Vermicompost From Poultry Waste for Sunflower Growth with a Sustainable Development SDG

Objective: This study aims to evaluate the effect of different chicken feather vermicompost rates collected from poultry waste and applied as organic fertilizers on the growth performance of sunflowers. Theoretical Framework: In this study, the chicken feather vermicompost was formulated based on the combination of chicken feathers, chicken dung, mushroom medium residue, and banana trunks. The completed chicken feather vermicompost was applied to the sunflower to evaluate the growth performance. Method: The methodology involved five different rates; T1 Control (300g organic fertilizer), T2 (200g chicken feather vermicompost), T3 (300g chicken feather vermicompost), T4 (400g chicken feather vermicompost), and T5 (500g chicken feather vermicompost). Total of 35 sunflower plants were applied with 5 treatments for 7 replications. Results and Discussion: The physio-chemical properties of chicken feather vermicompost, such as EC, pH, moisture, and temperature were optimal for decomposition organism growth and reproduction. The population and reproduction of Eudrilus eugeniae in vermicompost are influenced by all ingredients used in vermicomposting. The results show that the different chicken feather vermicompost rate affects sunflowers' growth performance. T5 exhibits the best performance in the number of flowers, number of leaves, relative chlorophyll content, fresh weight, and dry weight. Research Implications: By considering the chicken feather vermicomposting method, it is useful in reducing environmental pollution by managing waste efficiently. Originality/Value: This study provides a new technique for maximizing poultry waste through the chicken feather vermicomposting process and identifies the optimum rate of chicken feather vermicompost on growth performance of sunflowers for sustainable agriculture.

Impact of Microplastics on the Carbon and Nitrogen of Vermicompost

ABSTRACTThe impact of microplastics (MPs) on carbon (C) and nitrogen (N) content in vermicompost is not yet fully understood. This study aims to evaluate the effect of MPs on the carbon and nitrogen ratio in vermicompost, which is important for soil quality and health. The study was carried out using a control treatment and six variations of MPs in the vermicomposting process. Observations were carried out at certain time intervals for 60 days with routine measurements of pH, electrical conductivity (EC), seed germination index (GI), survival rate (SR), and C/N ratio. The results showed that all types of MPs caused a decrease in the C/N ratio compared to the control, with the high‐density polyethylene (HDPE) MPs treatment showing the most significant decrease (from 21 to 9.42). Observations also showed that MPs had an impact on reducing the SR parameters (6.88%–20.41%), pH (6.8–6.1), and EC (525.3–398 µs/cm) in vermicompost, which had an impact on the final product quality thereby reducing the GI (10%–28%). MPs have a significant effect on the C/N ratio in vermicompost, reducing the quality of the compost. This study provides new insights into how MPs can affect the composting process and the quality of the final product, important for sustainable agricultural practices and waste management.

Advanced Vermicomposting Modality: Microbial Acceleration to Improve Micronutrient Profile of Agricultural Residue Derived Compost

Advancing circular economies and self-reliant agricultural systems will critically depend on innovative strategies to optimize resource utilization and agro-waste recycling for the sustainability of food production. The present study is focused on the potential of vermitechnology with diverse substrate compositions in bioconverting lignocellulosic agricultural residues into nutrient-rich amendments. Trials of vermicomposting were carried out exploiting Eudrilus eugeniae and a fungal decomposer consortium, Pusa Decomposer. Treatments included T1: Gliricidia sepium leaves (GL), T2: Banana pseudostem (BP), T3: Rice straw (RS), T4: Rice husk (RH), T5 (RS + BP – 8:1 w/w), T6 (RH + BP - 8:1 w/w), T7 (RH + RS + BP – 4:4:1 w/w) and T8 (RH + RS + BP + GL – 4:4:0.5:0.5 w/w) with 3 replications in CRD. T2 expressed peak Mn, Zn and Cu values at 418.40 mg kg-1, 247.50 mg kg-1 and 55.12 mg kg-1, respectively. T3 reported summit Fe and B at 8669.50 mg kg-1 and 37.00 mg kg-1, respectively. It was found that the combination of RS and BP reported excellent nutrient solubilization and enhanced EC, which ratiocinates the role of substrate mix in determining vermicompost quality. These findings emphasize the importance of substrate selection and microbial augmentation with fungal decomposer consortia such as Pusa decomposer, which optimize the vermicomposting process for nutrient recovery and improved soil health.

Oriented regulation of earthworm production and vermicompost quality by carbon bioavailability management

Vermicomposting is an efficient bioconversion technology for recycling nutrients from organic waste materials. The biodegradability of raw materials has a significant impact on the earthworm transformation product. However, the management of carbon bioavailability is often overlooked during the vermicomposting process due to the varying degradability of C-rich source in different organic waste. This research aims to investigate the impact of different bioavailable carbon compositions on vermicomposting and to develop a strategy for efficient carbon management. The study involved systematic vermicomposting using four different biodegradable carbon sources (pineapple peels, rice straw, tomato straw, and sawdust) with varying carbon‑nitrogen ratios (ranging from 24 to 42). The earthworm production and vermicompost quality were comprehensively evaluated, along with the influence of carbon components on microbial community structure. The results indicated that the optimal vermicomposting treatments were achieved at PCM24, RCM30, TCM30, and MCM30 treatments. Maintaining an approximate ratio of 1:(0.5–1.3) between available and recalcitrant carbon components based on the optimal carbon‑nitrogen ratio was found to be optimal for regulating vermicomposting products. Increasing the proportion of available carbon enhanced the quality of vermicompost fertilizer, while a higher proportion of recalcitrant carbon could improve earthworm biomass production efficiency. Labile carbon proportion I (LCP1) and available carbon component (ACC) were identified as key indicators in influencing the formation of microbial community structure. Different carbon compositions led to the specific development and formation of microbial communities, further resulting in significant variations in vermicompost quality under the mediation of microbes. This study, for the first time, clarifies the impact of vermicomposting performance and microbial community from the perspective of carbon bioavailability, which is of great significance for the oriented regulation the vermicomposting efficiency and product in practice.

The Integration of Phosphorus-Solubilizing Rhizobacteria, Eisenia fetida and Phosphorus Rock Improves the Availability of Assimilable Phosphorus in the Vermicompost

Due to increasing soil degradation caused by unsustainable agricultural practices and the continued demand for quality food for the human population, it is imperative to find sustainable strategies for high-quality food production. For this reason, the objective of the present study was to evaluate the interaction between the factors of consortium of phosphorus-solubilizing rhizobacteria, addition of phosphate rock and worm load in horse manure to produce an organic fertilizer fortified with phosphorus. For this, consortia of phosphate-solubilizing rhizobacteria of the genus Bacillus (Bacillus aryabhattai, Bacillus subtilis and Bacillus cereus) isolated from the rhizosphere of Distichlis spicata were inoculated. Igneous phosphate rock (0 and 2%) was added in the vermicomposting process (with 25 and 50 g of E. fetida worms per kg of horse manure). The results obtained show that there is a significant interaction between the factors of inoculation with bacterial consortia (1 × 108 CFU mL−1), phosphate rock (2%) and earthworm biomass (50 g kg−1 of manure), and that this interaction promotes the production of assimilable forms of phosphorus for plants (such as monobasic phosphate ions H2PO4−1 or dibasic phosphate ions HPO4−2) within the vermicomposting process, having as a product an organic substrate supplemented with the optimal nutritional requirements for the development and growth of crops. This work can serve as a basis to produce high-quality organic fertilizer. However, field studies are required in order to observe the impact of vermicompost on the yield and quality of the fruits, and it can be compared with other types of fertilizers and the relevance of their use in different types of climates.

Study of the characteristics of soil mixtures obtained by vermicomposting

Vermicomposting is a sustainable and environmentally friendly element of organic waste management. Being a biological processing method involving a complex of soil organisms, vermicomposting requires the selection of conditions for the cultivation of transformer organisms, primarily dung worms (lat. Eisenia fetida). The duration and quality of the formation of the final product are influenced by the physicochemical conditions of worm cultivation, the composition of the starting material, methods of its placement, etc. We studied the influence of the composition of the substrate and the conditions of cultivation of Eisenia fetida on the characteristics of the resulting vermicompost in conditions of laboratory experiment. The biological characteristics of soil mixtures obtained by vermicomposting were studied, taking into account the physicochemical factors (humidity, pH, temperature) of their formation. It has been shown that the composition of the mixture significantly affects the characteristics of the vermicomposting process and the biological properties of the resulting product.

Bioconversion of cow manure through vermicomposting: effects of tylosin concentration on the weight of worms and manure quality

This study investigated batch-fed vermicomposting of cow manure, with a specific focus on assessing the effects of tylosin on the weight of earthworms and the overall quality of the resulting manure. Five reactors, including three concentrations of tylosin (50, 100, and 150 mg/kg) and two control reactors, were employed. Residual tylosin concentrations were measured using high-performance liquid chromatography (HPLC). Quality parameters such as pH, temperature, volatile solids (VS), organic carbon content (OCC), electrical conductivity (EC), ash content, C/N ratio, total Kjeldahl nitrogen (TKN), and microbial content were evaluated. The toxicity and maturity of vermicompost were assessed by determining the germination index (GI). The study also monitored variations in the earthworm’s weight. The results demonstrated a decreasing trend in VS, OCC, C/N, and fecal coliforms, along with increased pH, EC, ash content, and TKN during the vermicomposting process. Furthermore, investigations revealed significant reductions in the reactors with tylosin concentrations of 50, 100, and 150 mg/kg, resulting in the removal of 98%, 90.48%, and 89.38% of the initial tylosin, respectively. This result confirms the faster removal of tylosin in reactors with lower concentrations. Degradation of tylosin also conforms to first-order kinetics. The findings showed a significant influence of tylosin on the weight of Eisenia fetida earthworms and the lowest antibiotic concentration led to the highest weight gain. Finally, the high percentage of germination index (90–100%) showed that the quality and maturity of vermicompost is by national and international standards.

Comparative Study of Vermicomposting: Apple Pomace Alone and in Combination with Wheat Straw and Manure

Considering the sporadic number of scientific studies on vermicomposting apple pomace waste, this research conducts a comparative analysis of vermicomposting processes using Eisenia fetida, focusing on apple pomace both independently and in combination with wheat straw and/or manure (experiment 1: 60% apple pomace and 40% cattle manure; experiment 2: 60% wheat straw and 40% cattle manure; experiment 3: 80% apple pomace, 10% wheat straw, and 10% cattle manure; and experiment 4: 100% apple pomace). After a 240-day substrate transformation period, all four variations of vermicompost produced demonstrated favorable sensory properties, along with high microbiological and physicochemical quality. Throughout the vermicomposting process, the pH of all vermicomposting mixtures changed, converging towards approximately neutral values by the process’s conclusion. There was an increase in dry matter content, as well as total N, P, K, Ca, and Mg, along with organic matter. Notably, the levels of heavy metals (Zn, Cu, Cd, and Pb) in both the vermicomposting materials and resulting vermicomposts remained significantly below the maximum permissible levels stipulated by Republic of Serbia and European Union legislation, which is directly linked to the ecological origin of the raw materials used. The microbiological quality of the final vermicomposts was deemed satisfactory. Over time, there was a decrease in the counts of aerobic mesophilic bacteria as well as Escherichia coli. The counts of sulfite-reducing clostridia in all substrates remained below 102 CFU/g, while Salmonella spp. and Listeria monocytogenes were not detected in either the composting materials or the resulting composts. The vermiculture of apple pulp exhibited advantageous characteristics, notably a shortened vermicomposting period (150 days) compared to other agricultural waste. This reduction in processing time contributes an additional layer of advantage to the overall quality and efficiency of the resulting vermicompost.

Effects of Vermicomposting on Compost Quality and Heavy Metals：A Meta-analysis

In order to comprehensively evaluate the effects of vermicomposting on compost quality and the conversion of heavy metals under different control conditions, 109 studies were reviewed. The effects of earthworm species, pre-compost time, ventilation methods, initial C/N, initial pH, and initial moisture of the raw materials on compost quality and the heavy metal toxicity were quantitatively discussed during the vermicomposting process through Meta-analysis. The results showed that the six subgroups of factors all showed obvious influences on the compost quality and heavy metal toxicity. After vermicomposting, the contents of NO3--N (116.2%), TN (29.1%), TP (31.2%), and TK (15.0%) were significantly increased, whereas NH4+-N (-14.8%) and C/N (-36.3%) were significantly decreased. Meanwhile, the total amount of Cu and Cr of the final compost and their bioavailability were significantly reduced. Considering the influences of grouping factors on compost quality and heavy metals, it is recommended to adjust the initial moisture of pile materials to 70%-80%, C/N to 30-85, and pH to 6-7 and to conduct pre-composting for 0-15 d; additionally, vermicomposting should be naturally placed when the composting is aimed at promoting the compost quality. If the main purpose is to weaken the perniciousness of heavy metals in the raw material, it is recommended to adjust the initial moisture of the material to 50%-60%, C/N to less than 30, and pH to 7-8; to conduct no pre-compost; regularly turn the piles; and use the earthworm Eudrilus eugeniae for vermicomposting.

Effect of conventional and biodegradable microplastics on earthworms during vermicomposting process.

The potential effect of microplastics is an increasingly growing environmental issue. However, very little is known regarding the impact of microplastics on the vermicomposting process. The present study explored the effect of non-biodegradable (low density polyethylene; LDPE) and biodegradable (polybutylene succinate-co-adipate; PBSA) microplastics on earthworm Eisenia fetida during vermicomposting of cow dung. For this, earthworms were exposed to different concentrations (0, 0.5, 1 and 2%) of LDPE and PBSA of 2mm size. The cow dung supported the growth and hatchlings of earthworms, and the toxicity effect of both LDPE and PBSA microplastics on Eisenia fetida was analyzed. Microplastics decreased the body weight of earthworms and there was no impact on hatchlings. The body weight of earthworm decreased from 0 to 60th day by 18.18% in 0.5% of LDPE treatment, 5.42% in 1% of LDPE, 20.58% in 2% of LDPE, 19.99% in 0.5% of PBSA, 15.09% in 1% of PBSA and 16.36% in 2% of PBSA. The physico-chemical parameters [pH (8.55-8.66), electrical conductivity (0.93-1.02 (S/m), organic matter (77.6-75.8%), total nitrogen (3.95-4.25mg/kg) and total phosphorus (1.16-1.22mg/kg)] do not show much significant changes with varying microplastics concentrations. Results of SEM and FTIR-ATR analysis observed the surface damage of earthworms, morphological and biochemical changes at higher concentrations of both LDPE and PBSA. The findings of the present study contribute to a better understanding of microplastics in vermicomposting system.

Advancing Agricultural Sustainability: Vermicomposting as a Biochemical Pathway for Improved Soil Health and Climate Resilience

This comprehensive review explores the multifaceted role of vermicomposting in sustainable agriculture, emphasizing its biochemical processes and impact on soil systems. Beginning with the concept, the document delves into the intricacies of the vermicomposting process, including the selection of suitable earthworm species for vermiculture. It further examines the biochemical transformations that occur during vermicomposting, such as the optimization of the carbon to nitrogen ratio, alterations in organic carbon content, and the modulation of soil pH and electrical conductivity. The accumulation of heavy metals and the transformation of nitrogen and phosphorus are also discussed, alongside the process of humification. Subsequently, the profound effects of vermicompost on soil properties, highlighting its influence on physical characteristics, organic matter content, mineralization, and nutrient dynamics, as well as the enhancement of humus content was deeply reviewed. The document also investigates the implications of vermicomposting on plant growth and yield, providing insights into its potential to increase agricultural productivity. Additionally, the review addresses the impact of vermicomposting on greenhouse gas emissions, underscoring its significance in the context of climate-smart farming practices. Arising from detailed synthesis of the findings, vermicomposting is a pivotal component of climate-resilient agriculture, offering a pathway to healthier soil ecosystems and a sustainable future.

Effect of Biochar on Vermicompost Production: Chemical, Biochemical, and Biological Properties

Farm and industrial residues must be adequately managed to avoid negative environmental implications. In this study, our objective was to evaluate (i) the impact of the co-production of vermicompost using grape bagasse and biochar (BC) on the yield and biochemical, chemical, and biological properties of vermicompost; (ii) the effect of BC on earthworms (Eisenia fetida Sav.). The vermicompost was co-produced over 5 months (n = 4 per treatment) using (i) grape bagasse as the substrate, (ii) earthworms (Eisenia fetida Sav.), and (iii) three BCs (eucalyptus sawdust BC, pig manure BC, and carbonaceous material from poultry litter CM) at 2% (w/w). A control without BC was included. The chemical, microbiological (activity and respiration), enzymatic properties, and enzymatic indices were characterized. After the incubation period, vermicompost yield increased with the application of the three BCs (25% on average). The number of adult earthworms was not affected by any of the BCs. Compared to treatments without BC, those with pig manure BC and eucalyptus BC resulted in maintained or significantly decreased enzymatic activity, indicating that the vermicompost was at an advanced stage of maturity. Eucalyptus BC significantly enriched the C content of the vermicompost by 4.3%, maintaining respiration rates at 18% lower than the treatment without BC. Additionally, pig manure BC generated the lowest respiration rate in the vermicompost (20% lower). We conclude that BC has a positive influence on the vermicompost process, stabilizing organic matter (especially pig manure BC) and improving the potential of vermicompost to store C (when high-C-content BCs are applied).

Influence of Eisenia fetida on the Nematode Populations during Vermicomposting Process

Vermicomposting stands as a sustainable and environmentally friendly waste management practice, leveraging the metabolic prowess of earthworms to facilitate the decomposition of organic matter into nutrient-rich compost. The aim of this experiment was to study the influence of Eisenia fetida on the density and the tropic structure of a nematode community during the vermicomposting process over a period of 3 months. Sewage sludge and green waste served as composting substrates. Overall, six compost variants were prepared consisting of three variants incorporating E. fetida and three control variants lacking E. fetida. Throughout the investigation, samples were gathered on a monthly basis, with each variant undergoing three repetitions. The aim was to isolate nematodes, determine the population density of the five trophic groups, and identify the dominant community. The anaysis was conducted employing both microscopic examination and molecular metabarcoding (NGS). It was shown that the bacterial-feeding community maintained dominance. The introduction of E. fetida into the compost led to a significant rise in the abundance of Diplogasteridae. In the variant without E. fetida, the amount of Diplodasteridae exceeded 0.1% only after the 30th (C3) or the 60th (C1, C2) day of composting, while in the compost with E. fetida, they were present in large amounts (ranging from 11.0% to 28.0%) already on the 30th day of composting. The introduction of Eisenia fetida also led to a notable reduction in H. gingivalis with significant implications for mitigating the risk of halicephalobiosis. The introduction of E. fetida resulted in reducing H. gingivalis to levels below 0.1% in all compost variants.

Metagenomic insight into the mechanisms of accelerated di-2-ethylhexyl phthalate (DEHP) degradation in vermicomposting

Earthworms can expedite di-(2-ethylhexyl) phthalate (DEHP) degradation in soils, but limited information is available on the key DEHP-degradation pathways and related genes during the vermicomposting process. In this study, DEHP degradation, degradation-related genes and bacterial communities were investigated by metagenomic analysis. DEHP degradation efficiency was significantly and 65.69% higher in vermicomposting treatment than natural soils. Earthworm supplement remarkably increased the contents of humic acid, humus and fulvic acid in soils. Both humic acid and earthworm gut positively stimulated soil microbes potentially responsible for DEHP degradation. Betaprotebacteria, Acidobacteria, Variovorax, Hydrogenophaga, Limnobacter, Ramlibacter, Pseudomonas, Acinetobacter, Paracoccus and Achromobacter significantly contributed to DEHP degradation pathways. From functional gene analysis, there were remarkable differences in dominant DEHP degradation pathways between soils (catechol pathway), earthworm cast (protocatechuate pathway), and earthworm gut (protocatechuate and catechol pathways). Our findings proposed two possible mechanisms of earthworms in accelerating DEHP degradation, stimulating the activities of indigenous degraders to augment the catechol pathway in soils and providing an extra protocatechuate pathway in earthworm gut. This study, for the first time, offers new insights into the impacts of vermicomposting on DEHP degradation genes and pathways, providing valuable scientific evidence for improving DEHP bioremediation in contaminated agricultural soils.

Comparative investigation on synergistic changes in enzyme activities during vermicomposting of cereal grain processing industry sludge employing three epigeic earthworm species.

The management of cereal grain processing industry sludge through vermicomposting is an emerging prospect for researchers interested in the green economy. This work is designed to enumerate the enzymatic influence of three epigeic earthworm species - Eisenia fetida, Eudrilus eugeniae, and Perionyx excavatus on the industrial sludge. The vermicomposting experiment was conducted in plastic pots by blending the waste materials with 5% cow dung. The dynamics in activities of cellulase, amylase, invertase, phosphatase, protease, dehydrogenase, and urease were studied on 15days intervals till the harvesting period. The periodical observations confirmed that the enzyme activities (in terms of μg reducing sugar/g/hr) of cellulase (26.45-128.09) amylase (205.43-878.96), invertase (105.32-841.65), phosphatase (85.29-435.54), protease (64.21-359.47), dehydrogenase (111.17-587.72), and urease (94.16-476.71) was low in the first 15days of the vermicomposting experiment followed by a sharp increase in the next 45days accompanied by a steady decline until the harvesting is carried out. Emerging statistical tools such as principal component analysis were employed to study the synergistic deviations of the enzymes during the vermicomposting process. The results confirmed that the enzyme activity efficiently influences the bio-oxidation of industrial waste at an individual level as well as synergistic level thereby allowing the vermicompost to mature much before the appearance of any physical symptoms on the surface of the vermireactors.

Urban sewage sludge stabilization by alkalization-composting-vermicomposting process: Crop-livestock residue use.

Waste management practices are vital for human health and the environment in a world where natural resources stress is expected to increase with the growth of population. Our study aimed to evaluate the potential use of crop-livestock residue as a bulking agent associated with the ideal level of hydrated lime for the stabilization and sanitization of urban sewage sludge through the alkalization-composting process. Therefore, we determined the alkalization efficiency on the heavy metal concentration in urban sewage sludge, quantified the viable eggs of helminths in pure and alkalized sludge, and measured the rate of earthworms (Eisenia fetida) surviving in the vermicomposting process using different levels of alkalized urban sewage sludge associated with crop-livestock residue. Four sequential trials were carried out in a completely randomized design with three replicates. The lime alkalization reduced the levels of Ba, As, Pb, Cu, Cr, Mo, Ni, and Zn compared to the pure urban sewage sludge. Using 30% w/w of lime in the urban sewage sludge (SS-30) for composting process reduced the viable helminth eggs by 71, 72, and 69% for sugarcane bagasse (Saccharum officinarum; SB), fresh chopped Napier-grass (Pennisetum purpureum; NG), and bovine ruminal content (BR), respectively. The ideal level of hydrated lime for stabilization and sanitization of urban sewage sludge was found to be 30%, which was able to reduce the heavy metals. The residues have the potential as a bulking agent for the composting of urban sewage sludge when associated with alkalization. The lime alkalization decreases the total number of helminth eggs and the number of viable eggs. The possibility of starting a vermicomposting using the mixtures is promising, evidenced by the earthworm survival in composting urban sewage sludge mixed with crop-livestock residues after 45 days of composting. The earthworm survival is maintained by an association of at least 80% of the crop-livestock residues.